# Adding, Subtracting, Multiplying, and Dividing

## Presentation on theme: "Adding, Subtracting, Multiplying, and Dividing"— Presentation transcript:

Fractions Adding, Subtracting, Multiplying, and Dividing

When adding or subtracting fractions with like denominators, you will keep the denominator and add the numerators together. When adding or subtracting fractions with unlike denominators, you will need to turn them into common denominators first and then add the numerators.

Now you try adding and subtracting like denominators.
Figure out the problem first and then use the mouse key to view the answer.

Some things to remember: The denominators must always be the same before you can add or subtract the numbers together. Determine what the common denominator should be and turn each fraction into a fraction with the common denominator. Then add or subtract. Common denominators are always needed before you can add or subtract fractions.

Converting to like denominators
A quick review of how to put fractions into common denominators First determine what the common denominator is going to be. Convert the fractions to the common denominator by multiplying the numerator and denominator by the factor needed to make the common denominator equal. Follow basic rules to complete the problem.

Example

Remember to always reduce to the lowest terms.

P R A C T I E Work out the problems first, and then click here to see if you got the right answer.

A N S W E R

Multiplication When you are multiplying or dividing fractions, there is no need to have the same denominators. You can cross-cancel like numbers You can multiply straight across and reduce your answer to lowest terms

Examples: You just multiply the numerators together and then the denominators together. The answer is in lowest terms already so I don’t have to reduce. For this problem, I was able to reduce the numbers (working cross-wise) to help reduce the fractions before multiplying. I have also shown that you can just multiply straight across and still get the same answer.

P R A C T I E Work out the problems first, and then click here to see if you got the right answer.

A N S W E R

Division When dividing fractions such as: you will first need to change it to a multiplication problem by rewriting the first fraction, change the division sign to multiplication and “flip” the fraction that follows the division sign.

Changing from division to multiplication
Write down the first fraction as it appears Change the division sign to a multiplication sign “Flip” or take the inverse of the fraction that follows the division sign. Multiply as usual.

P R A C T I E Work out the problems first, and then click here to see if you got the right answer.

A N S W E R